All About Powder Processing

powder processing is a term used in the automotive industry to refer to an alternative to traditional liquid paint where a colored polymer is instead applied as a powder and then cured. The polymer is not chemically bonded by a binder nor by the evaporation of a solvent. It is nonadhesive at room temperature, adhering to the metal body of a car only by electrostatics. It becomes permanent because of heat treatment.

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Powder processing is ideal for car parts before assembly because solid metal pieces are easy to throw into an oven. It is hard to use powder processing on an entire car unless it is just the metal frame. It cannot be easily used as a spot treatment because the powder would have to be heated and baked in just that one spot. It is attractive for factories as it removes the need to vent a solvent.


Powder processing did not happen overnight, and it is a technology that is in a constant state of development. It is not new but is not considered old fashion because it is still a highly economical way to create a hard coating on a metal surface. The first powdered paints were used in the 1940s and were relatively primitive organic particles. Petroleum derivatives such as plastics became the basis for powdered paint.


Over the years, many synthetic formulas have been experimented with. Most plastics will adhere to a rough surface if first applied and then melted. Plastics vary significantly in their hardness and melting temperature, and many polymers are entirely synthetic. Developing a new powdered paint almost always begins in a laboratory where a substance is applied as a coat and then heated in a small test oven to see what works best.


Once a material has been selected, different dyes are also added in order to produce color. These dyes must bond well with a given plastic or enamel during curing. For this reason, different colors are tested individually just to make sure everything works well. After testing, a new powder paint has to first be tested with prototype factory equipment.


If scale equipment works exactly as expected, then a larger assembly line will be designed by an engineer. It is expensive to produce new factory equipment, but each type of plastic has specific handling requirements. The equipment has to melt plastic at just the right temperature and then mill large beads into powder of the desired consistency. The equipment has to resist jamming or fowling.


Powder applicators follow a similar logic. Handheld applicators might be adjustable and are not precise, but applicators used in factories are carefully calibrated for the exact weight of the powder to achieve the most efficient spray. Often robotic applicators are adjusted extensively before the beginning of an assembly line.


Powder processing is still in a state of development. New materials might be more durable or cheaper. New applicators might be developed for intelligent robots that adapt to room conditions and are not merely repeating an exact sequence of movements. For the amateur painter, options for the home garage might become more practical.